Periodontitis and osteoarthritis (OA) are major public health concerns that result in decreased quality of life among middle‐aged and older adults. This nationwide population‐based study aimed to examine whether the severity of periodontitis is related to osteoarthritis (OA) according to type 2 diabetes.

This study included 3,527 participants aged ≥50 years from the Korean National Health and Nutrition Examination Survey. OA was defined as Kellgren–Lawrence grade ≥2 on the knee or hip area’s radiographic images with joint pain. The odds ratios (ORs) and 95% confidence intervals (CIs) for OA according to the severity of periodontitis, stratified by type 2 diabetes, were calculated using multiple logistic regression analyses. Participants with type 2 diabetes were more likely to have OA as the severity of periodontitis increased (nonsevere periodontitis: 1.23 [0.67–2.32]; severe periodontitis: 3.01 [1.51–5.84]) after adjusting for hypertension, household income, smoking status, education level, regular exercise, alcohol consumption, body mass index, sex, age, and frequent tooth‐brushing.

In conclusion, severe periodontitis was positively and significantly associated with OA in middle‐aged and older individuals with type 2 diabetes. The research findings suggest that the oral inflammation manifesting in periodontitis might be partially involved in the pathogenesis of OA, particularly in patients with type 2 diabetes.